如何为 HTML 选择设置默认值？
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How to set default value for HTML select?
提问by Saman
I have a HTML select like this:
我有一个像这样的 HTML 选择：
<select>
<option>a</option>
<option>b</option>
<option>c</option>
</select>
and I have a variable named tempin my JavaScript:
temp我的 JavaScript 中有一个名为的变量：
var temp = "a";
Now I want to set the value of the option that is equal to temp as default value for my select.
现在我想将等于 temp 的选项的值设置为我的选择的默认值。
How can I do it?
我该怎么做？
回答by Sébastien
You first need to add values to your selectoptions and for easy targetting give the selectitself an id.
您首先需要为您的select选项添加值，并为方便定位给它select本身一个id.
Let's make option bthe default:
让我们将选项设为b默认值：
<select id="mySelect">
<option>a</option>
<option selected="selected">b</option>
<option>c</option>
</select>
Now you can change the default selected value with JavaScript like this:
现在，您可以使用 JavaScript 更改默认选定值，如下所示：
<script>
var temp = "a";
var mySelect = document.getElementById('mySelect');
for(var i, j = 0; i = mySelect.options[j]; j++) {
if(i.value == temp) {
mySelect.selectedIndex = j;
break;
}
}
</script>
See it in action on codepen.
回答by Portland Runner
Note: this is JQuery. See Sébastien answer for Javascript
注意：这是 JQuery。请参阅 Sébastien 对 Javascript 的回答
$(function() {
var temp="a";
$("#MySelect").val(temp);
});
<select name="MySelect" id="MySelect">
<option value="a">a</option>
<option value="b">b</option>
<option value="c">c</option>
</select>
回答by user2923853
You should define the attributes of optionlike selected="selected"
您应该定义optionlike selected="selected"的属性
<select>
<option selected="selected">a</option>
<option>b</option>
<option>c</option>
</select>
回答by Naveen Kumar Alonekar
Simplay you can place HTML selectattribute to option
alike shown below
Simplay 您可以将 HTML选择属性放置到
a如下所示的选项中
Define the attributes like selected="selected"
定义属性，如 selected="selected"
<select>
<option selected="selected">a</option>
<option>b</option>
<option>c</option>
</select>
回答by siddharth jambukiya
you can define attribute selected="selected" in Ex a
您可以在 Ex a 中定义属性 selected="selected"
回答by Gavin
You could use...
你可以用...
<option <?= ($temp == $value) ? "SELECTED" : "" ?> >$value</opton>
Edit: I thought I was looking at PHP questions... Sorry.
编辑：我以为我在看 PHP 问题...抱歉。
